Elastomer cushion ring for a random tooth roller chain sprocket

Abstract

A sprocket is provided with a plurality of teeth spaced about its periphery, the sprocket including roots located between pairs of adjacent teeth. The roots have root radii defined as the distance between the center of sprocket and the point along the root closest to the sprocket center in the radial direction. Roots have three distinct radii. a cushioning material for receiving the impact while engaging a chain has a geometry means substantially following the contours of the sprocket teeth geometry.

Description

FIELD OF THE INVENTION [0001] The invention pertains to the field of cushion rings. More particularly, the invention pertains to elastomer cushion rings that are bonded to at least one side of a random tooth roller chain sprocket BACKGROUND OF THE INVENTION [0002] Randomized sprockets for roller chain are known. U.S. Pat. No. 6,155,943, which is hereby incorporated herein by reference, discloses a roller chain and sprocket drive with a randomized sprocket which modulates the roller position on the sprocket by varying the radial seating position of the roller while maintaining a constant chordal dimension between seated rollers. The roots between teeth of the sprocket have radii that vary between a nominal radius and a maximum radius and a minimum radius. This variation or randomization is intended to provide a noise modulation effect while avoiding the negative effects of high impact from conventional randomized sprockets. [0003] It is also known to use roller chain sprockets, which...

AI Technical Summary

Benefits of technology

[0011] A random tooth sprocket having contoured elastomer cushion ring having at least one cushion ring geometry each having a predetermined amount of interference with the roller chain pin links and bush links is provided. The different cushion ring geometries each changes the amount of interference with the chain for each incremental rotation of the sprocket. Full interference occurs at full chain engagement. The interference can occur abruptly or gradually during chain engagement. This can be used for tuning the noise, vibration and harshness (NVH) levels while minimizing negative effects. Negative effects includes durability concerns (e.g. tearing of the cushioning means) from too large an interference or applying the interference abruptly.

[0013] A random tooth sprocket having contoured elastomer cushion ring having the elastomer material reduces chain roller and / or bushing engagement impact forces thereby reducing noise and increases roller / bushing fatigue life.

[0014] Accordingly, a sprocket comprising a plurality of teeth spaced about its periphery, said sprocket including roots located between pairs of adjacent teeth is provided. Each of said roots have a root radius defined as the distance between the center of said sprocket and the point along said root closest to the sprocket center in the radial direction, and at least one of said roots have a first root radius, at least one of said roots have a second root radius, said second root radius being less than said first root radius. The first root radius and the second root radius are defined so that the distance between the centers of adjacent rollers will be substantially equal along the rollers seated in the sprocket roots. The sprocket further includes a cushioning material for receiving the impact while engaging a chain having a geometry means substantially following the contours of the sprocket teeth geometry.

Problems solved by technology

Repetitive sprocket tooth spacing is known to create undesirable chain engagement noise having orders that are related to the number of sprocket teeth.

A random tooth sprocket has both irregular angular spacing and varying pitch radii of the sprocket teeth which disrupts the repetitive chain engagement noise orders.

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